ignition switch

I have a 1974 TR 6....a little over two weeks ago I noticed when I turned the ignition switch key several times it would not start the engine ...nothing....turned again several times and it finally engaged the engine.....now two weeks later it has gotten worse....turned the key all the way on....nothing....tried again.....and again....finally after 30-45 sec it engaged the engine....any idea what is going on???...thanks,Gene